BeGeistert is a pretty casual event and anyone can attend.There will be a commonality between the two events and that can't really be avoided but a Waltercon will by definition be about Haiku and developers, Zeta and BeOS are as such off the menu. End users shouldn't be excluded but the event should be targeted at developers.
BeGeistert has various presentations most of which deal with "what", What was developed, what features were added etc. A developer conference should be more about "how" and "why", how this was achieved and why it was done that way.
As for the question of US Vs Europe Waltercon I don't think this should be an issue, you are likely to get a completely different audience at each event. Having one event on one side of the pond should not preclude one on the other, there is no reason (apart from possibly financing) not to have both.
So, how about having a more focused event with a range of talks on developer related subjects? If it's here I can offer multicore processors and / or Cell development (not Haiku specific but certainly relevant).
Also what about moving it to early next year (say January) so as not to clash with BeGeistert?
-- Nicholas Blachford www.ps3coderz.com www.blachford.info "Do not fear death, fear having not lived."